Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments
Four types (2D-video disdrometer: 2DVD; precipitation occurrence sensor system: POSS; micro-rain radar: MRR; and Joss–Waldvogel disdrometer: JWD) of sixteen instruments were collocated within a square area of 400 m<sup>2</sup> from 16 April to 8 May 2008 for intercomparison of drop size...
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doaj-54b65a4be45c417ca834dca88d6fa5c92020-11-25T02:37:27ZengMDPI AGRemote Sensing2072-42922020-04-01121167116710.3390/rs12071167Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated InstrumentsWei-Yu Chang0GyuWon Lee1Ben Jong-Dao Jou2Wen-Chau Lee3Pay-Liam Lin4Cheng-Ku Yu5Department of Atmospheric Sciences, National Central University, Taoyuan 32001, TaiwanDepartment of Astronomy and Atmospheric Sciences, Center for Atmospheric Remote sensing (CARE), Kyungpook National University, Daegu 41566, KoreaDepartment of Atmospheric Sciences, National Taiwan University, Taipei 10617, TaiwanNational Center for Atmospheric Research, Boulder, CO 80301, USADepartment of Atmospheric Sciences, National Central University, Taoyuan 32001, TaiwanDepartment of Atmospheric Sciences, National Taiwan University, Taipei 10617, TaiwanFour types (2D-video disdrometer: 2DVD; precipitation occurrence sensor system: POSS; micro-rain radar: MRR; and Joss–Waldvogel disdrometer: JWD) of sixteen instruments were collocated within a square area of 400 m<sup>2</sup> from 16 April to 8 May 2008 for intercomparison of drop size distribution (DSD) of rain. This unique dataset was used to study the inherent measurement uncertainty due to the diversity of the measuring principles and sampling sizes of the four types of instruments. The DSD intercomparison shows generally good agreement among them, except that the POSS and MRR had higher concentrations of small raindrops (<1.0 mm) and offered a better chance to observe big raindrops (>5.2 mm). The measurement uncertainty (<inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">σ</mi> </semantics> </math> </inline-formula>) was obtained quantitatively after considering the zero or non-zero measurement error covariance between two instruments of the same type. The results indicate the measurement uncertainties were found to be neither independent nor identical among the same type of instruments. The MRR is relatively accurate (lower <inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">σ</mi> </semantics> </math> </inline-formula>) due to large sampling volumes and accurate measurement of the Doppler power spectrum. The JWD is the least accurate due to the small sampling volumes. The <inline-formula> <math display="inline"> <semantics> <mi mathvariant="sans-serif">σ</mi> </semantics> </math> </inline-formula> decreases rapidly with increasing time-averaging window. The 2DVD shows the best accuracy of R in longer averaging time, but this is not true for Z due to the small sampling volume. The MRR outperformed other instruments for Z for entire averaging time due to its measuring principle.https://www.mdpi.com/2072-4292/12/7/1167drop size distributionuncertaintysampling volumedisdrometermeasuring principle |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Wei-Yu Chang GyuWon Lee Ben Jong-Dao Jou Wen-Chau Lee Pay-Liam Lin Cheng-Ku Yu |
spellingShingle |
Wei-Yu Chang GyuWon Lee Ben Jong-Dao Jou Wen-Chau Lee Pay-Liam Lin Cheng-Ku Yu Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments Remote Sensing drop size distribution uncertainty sampling volume disdrometer measuring principle |
author_facet |
Wei-Yu Chang GyuWon Lee Ben Jong-Dao Jou Wen-Chau Lee Pay-Liam Lin Cheng-Ku Yu |
author_sort |
Wei-Yu Chang |
title |
Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments |
title_short |
Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments |
title_full |
Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments |
title_fullStr |
Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments |
title_full_unstemmed |
Uncertainty in Measured Raindrop Size Distributions from Four Types of Collocated Instruments |
title_sort |
uncertainty in measured raindrop size distributions from four types of collocated instruments |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2020-04-01 |
description |
Four types (2D-video disdrometer: 2DVD; precipitation occurrence sensor system: POSS; micro-rain radar: MRR; and Joss–Waldvogel disdrometer: JWD) of sixteen instruments were collocated within a square area of 400 m<sup>2</sup> from 16 April to 8 May 2008 for intercomparison of drop size distribution (DSD) of rain. This unique dataset was used to study the inherent measurement uncertainty due to the diversity of the measuring principles and sampling sizes of the four types of instruments. The DSD intercomparison shows generally good agreement among them, except that the POSS and MRR had higher concentrations of small raindrops (<1.0 mm) and offered a better chance to observe big raindrops (>5.2 mm). The measurement uncertainty (<inline-formula>
<math display="inline">
<semantics>
<mi mathvariant="sans-serif">σ</mi>
</semantics>
</math>
</inline-formula>) was obtained quantitatively after considering the zero or non-zero measurement error covariance between two instruments of the same type. The results indicate the measurement uncertainties were found to be neither independent nor identical among the same type of instruments. The MRR is relatively accurate (lower <inline-formula>
<math display="inline">
<semantics>
<mi mathvariant="sans-serif">σ</mi>
</semantics>
</math>
</inline-formula>) due to large sampling volumes and accurate measurement of the Doppler power spectrum. The JWD is the least accurate due to the small sampling volumes. The <inline-formula>
<math display="inline">
<semantics>
<mi mathvariant="sans-serif">σ</mi>
</semantics>
</math>
</inline-formula> decreases rapidly with increasing time-averaging window. The 2DVD shows the best accuracy of R in longer averaging time, but this is not true for Z due to the small sampling volume. The MRR outperformed other instruments for Z for entire averaging time due to its measuring principle. |
topic |
drop size distribution uncertainty sampling volume disdrometer measuring principle |
url |
https://www.mdpi.com/2072-4292/12/7/1167 |
work_keys_str_mv |
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1724795577809502208 |